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diff --git a/Documentation/submodules.md b/Documentation/submodules.md new file mode 100644 index 0000000000..631e351303 --- /dev/null +++ b/Documentation/submodules.md @@ -0,0 +1,46 @@ +Use of git submodules in coreboot +================================= +coreboot uses git submodules to keep certain parts of the tree separate, +with two major use cases: + +First, we use a vendor tool by NVIDIA for systems based on their SoC +and since they publish it through git, we can just import it into our +tree using submodules. + +Second, lots of boards these days require binaries and we want to keep +them separate from coreboot proper to clearly delineate shiny Open Source +from ugly blobs. +Since we don't want to impose blobs on users who really don't need them, +that repository is only downloaded and checked out on explicit request. + +Handling submodules +------------------- +For the most part, submodules should be automatically checked out on the +first execution of the coreboot Makefile. + +To manually fetch all repositories (eg. when you want to prepare the tree +for archiving, or to use it without network access), run + + $ git submodule update --init --checkout + +This also checks out the binaries below `3rdparty/` + +Mirroring coreboot +------------------ +When running a coreboot mirror to checkout from, for full operation, you +should also mirror the blobs and nvidia-cbootimage repository, and place +them in the same directory as the coreboot repository mirror. + +That is, when residing in coreboot's repository, `cd ../blobs.git` +should move you to the blobs repository. + +With that, no matter what the URL of your coreboot repository is, the +git client (of a sufficiently new version) is able to pick up the other +repositories transparently. + +Minimum requirements +-------------------- +git needs to be able to handle relative paths to submodule repositories, +and it needs to know about non-automatic submodules. + +For these features, we require git version 1.7.6.1 or newer. |